These are just simple functions for drawing semi-transparent rectangles, pixels and iamges with an alpha channel.. Io can read an article about alpha channels here: http://en.wikipedia.org/wiki/Alpha_channel
Semi-transparent rectangles are just unifor-coloured bitmaps with a uniform alpha channel.

Sorry for that. I'll remove aunknown.c from the patch, as that is just another test file. I'm new to patching. france.320x240x16.bmp is now attached. It's a picture from google, since I didn't want to attach the original one.